Wrench

Abstract: A wrench for tightening a tightening member to another member by revolving the tightening member around its axis, wherein the wrench comprises an inner surface which is attached to the outer surface of the tightening member. On the inner surface, a recess is provided to store a wedge member and is configured by a continuous formation of a slack area and a wedge area. The wedge member is configured to wedge between the outer surface of the tightening member and the wall of the wedge area when the wrench body is rotated in the one direction, in order to place the wedge member in the wedge area, whereby the wrench and the tightening member are unified regarding the relevant direction, enabling the rotation of the tightening member in the relevant direction through the wrench.

Description: The present invention relates to a tool for tightening a revolving tightening member, such as a nut and bolt or a nut on a chucking device for machine tools, and in particular, to a wrench which can easily be attached to a tightening member. In the past, various kinds of tightening members such as nuts and bolts which are tightened when revolved around an axis have been known. Generally, edges are provided on the outer surface of the tightening member by, for example, forming the tightening member into a prismatic shape, such as a hexagon. A wrench or other tool comprising an open end to fit the shape of the tightening member can be attached to grasp the outer surface edges of the tightening member. By revolving the tool, the tightening member can be tightened. The above-mentioned mechanism can also be used for tightening nuts on chucking devices or cutting tool holders, i.e., where the outer surface of the tightening nut is knurled and a recess or engagement groove is formed to receive the wrench. However, placing a wrench on the edges or engagement grooves of a nut is both time consuming and burdensome. Moreover, the manufacturing process for such nuts is made more complex, as recesses and grooves on the tightening member must be formed, or the tightening member must be formed with an edged shape. Moreover, the relative angle of the wrench enabling it to connect with the edges or grooves of such nuts is so limited that if the space around the nut is insufficient, the wrench may not be able to connect to the nut, depending on the angle of the nut. US-A-3906822 discloses an open end one-direction wrench according to the preamble of claim 1 in which turning of the wrench on for example a nut in one direction forces a plurality of gripping members to tighten, and turning in the other direction forces the gripping members away from the nut. Therefore, this invention, in order to solve these problems, provides a wrench which can be easily attached to a tightening member, which enables easier manufacturing of a tightening member, and which can easily tighten a tightening member even when there is limited space in the area around the tightening member. According to the present invention there is provided a wrench for tightening a tightening member to another member by rotating said tightening member around its own axis, comprising: a body having an inner surface to be attached to an outer surface of said tightening member; at least one rotatable wedge member provided on said inner surface of said body having a wedged state in which it wedges between said outer surface of said tightening member and said inner surface of said body at least one recess with a circularly-curved cross section formed on said inner surface of said body for receiving said at least one wedge member, each recess including a slack area for housing said wedge member in a non-wedged state and a first wedge area flanking one side of said slack area, the first wedge area being for housing said wedge member in said wedged state, the depth of said slack area being greater than that of said first wedge area; and a retainer disposed on said inner surface of said body and having a respective aperture to maintain said at least one wedge member in a predetermined position along said inner surface, said retainer being configured so as to be movable in the direction of the circumference of said inner surface of said body to a predetermined extent, for moving said wedge member from said slack area to said first wedge area upon rotation of said body in at least one direction whereby said wedge member protrudes from said retainer into the wrench opening is which the tightening member is received characterised by:- said at least one recess having a second wedge area flanking said slack area on a side opposite said one side; and at least one pin-like stopper for preventing said at least one wedge member and the retainer from moving from said slack area to said second wedge area. In one embodiment, said at least one wedge member is cylindrical in shape. In another embodiment, said at least one wedge member is spherical in shape. Preferably, said inner surface of said body is formed so as to surround completely said outer surface of said tightening member. Advantageously the retainer is annular and the wrench further comprises a biasing means for biasing said retainer such that said at least one wedge member is biased from said slack area towards said wedge area, said biasing means comprising a ring-shaped spring corresponding in shape to that of said retainer. As described , the wedge member wedges between the outer surface of the tightening member and the inner surface of the wrench by rotating the wrench body in at least one direction, whereby the wrench and the tightening member are unified regarding the same direction to enable the rotation of the tightening member in the same direction as the wrench. Therefore, providing edges on the outer surface of the tightening member to receive the wrench is not necessary, enabling the formation of a tightening member in a cylindrical shape. As a result, as the necessity of providing edges, etc. on the outer surface of the tightening member is eliminated, it is no longer time consuming or difficult to attach the wrench to the tightening member, and manufacture of the tightening member becomes easier. Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 illustrates a partially cut out cross section of a chuck to which the present invention is applied; Fig. 2 is a front view of a first wrench not in accordance with the present invention; Fig. 3 is a partially cut out side view with the wrench of Fig. 2 attached to a chuck to be tightened; Fig. 4 is a cross sectional view taken along IV - IV of Fig. 3; Fig. 5 is an enlarged view of the wedge mechanism before attaching the wrench to the rotating tube; Fig. 6 is an enlarged view of the wedge mechanism before the wrench is attached to the rotating tube; Fig. 7 is an enlarged view of the wedge mechanism when the wedge member wedges between the wall of the wedge area and the outer surface of the rotating tube; Fig. 8 is a side view with the wrench attached to a chuck to be loosened; Fig. 9 is a cross section of the key elements of a second wrench; Fig. 10 is a partially cut out plan view illustrating a wrench according to an embodiment of the present invention; Fig. 11 is a cross section taken along XI - XI of Fig. 10; Fig. 12 is a cross section of the wrench of Fig. 10 at the same position as that shown in Fig. 9; Fig. 13 is a perspective view of the spring used in the wrench of Fig. 10; An embodiment of the present invention will be described in connection with Figures 10 to 13 by way of example only with reference to a tool holder i.e., a chuck, to secure a machine tool, such as a drill. In Fig. 1, numeral 10 denotes generally a chuck body. The chuck body 10 is to be attached to a machine center or other main spindle head (not shown), and comprises a tapered shank portion 12 which tapers toward the base end, i.e., to the left in Fig. 1; a chuck placement flange portion 14 formed next to the tapered shank portion 12; and a chuck tube 16 which projects toward the top end portion from the flange portion 14 as a part of the chuck. This chuck tube 16 comprises an inner surface 18 to receive a straight shank portion or a collet of the machine tool, and an outer surface 20 which is tapered toward the top end portion. Rotatable on the outer surface 20 of the chuck tube 16 is a cylindrical rotating tube or tightening nut 22 as a tightening member. This rotating tube 22 has an inner surface 24 tapered toward the top end portion corresponding to the outer surface 20 of the chuck tube 16. Around the base portion of the rotating tube 22, a circumferential stopper 25 projects slightly in the outward direction at its radius to prevent the falling off of a below-mentioned wrench from the rotating tube 22. A plurality of rotatable needle rollers 26 are provided between the rotating tube 22 and the chuck tube 16, which are held by a retainer 28. Through rotation of the rotating tube 22, the needle rollers 26 rotate and at the same time revolve in a helix around the outer surface 20 of the chuck tube 16, whereby the chuck tube 16 is able to grasp the tool. Numeral 30 indicates a sealing member and numeral 32 indicates a stop ring, both of which prevent the needle rollers 26 from falling off. The outer surface 23 of the rotating tube 22 is smooth, and is neither knurled nor provided with any recess for receiving a conventional wrench, as opposed to a conventional rotating tube of a chuck. Fig. 2 illustrates a wrench 34 for rotating the rotating tube 22 to tighten the chuck tube 16 onto a machine tool. This wrench is not an embodiment of the present invention and is only usefull for understanding the invention. This wrench 34 has a main body portion 39, which includes a wrench opening 40, the cross section of which is a circle having an inner diameter slightly larger than the outer diameter of the rotating tube 22 to enable insertion of the rotating tube 22, and a pair of handles 36 uniformly provided on the main body portion 39. A wedge mechanism is provided on the inner surface 38 of the wrench opening 40. As shown in Fig. 4, the wedge mechanism comprises a plurality of cylindrical wedge members 44 disposed on the circumference of the inner surface 38 within a certain distance from each other, recesses 42 to receive each of the wedge members 44, and coil springs 46 to bias each of the wedge members 44 in the counter-clockwise direction in Fig. 4. Each of the recesses 42 is formed to receive the cylindrical wedge members 44, caving in from the inner surface 38 of the wrench opening 40, and extending along the axis at a predetermined length (i.e., in the direction perpendicular to the paper in Fig. 4). Each recess 42 is configured to define a slack area 41 which has a rather deep recess, and a wedge area 43 adjacent to the slack area 41 with a shallower recess than the slack area 41. The volume of the slack area 41 is sufficient for the wedge member 44 to freely roll, and the depth of the slack area 41 is formed slightly smaller than the diameter of the wedge member 44 so that a portion of the wedge member 44 projects from the inner surface 38 toward the center. The depth of the wedge area 43 is rather shallow so that the wedge member 44 wedges between the wedge area 43 and the outer surface 23 of the rotating tube 22. The spring 46 is retained in a spring housing 47, and biases the wedge member 44 in the counter-clockwise direction, i.e., from the slack area 41 toward the wedge area 43, and under normal conditions where the body 39 is not attached to the rotating tube 22, the wedge member 44 is located at the wedge area 43 as shown in Fig. 5. A projection 48 is formed at the end of the recess 42 opposite the spring housing 47, and the wedge member 44 is prevented from falling off by the projection 48 and the biasing force of the spring 46. Now the operation of this wrench is explained. First of all, the wrench opening 40 is placed around the outer surface 23 of the rotating tube 22 of the chuck body 10 as shown in Fig. 3. At this point, the wedge member 44 is in contact with and pushed by the rotating tube 22 from the wedge area 43 to the slack area 41, i.e., from the state shown in Fig. 5 to that shown in Fig. 6, against the biasing force of the spring 46. As this slack area 41 holds the wedge member 44 with slack, the wedge member 44 does not wedge between the rotating tube 22 and the inner wall of the recess 42. Therefore, in placing the wrench opening 40 over the rotating tube 22, although the outer surface of the wedge member 44 is in contact with the outer surface 23 of the rotating tube 22, the wedge member 44 does not interfere with the placing operation itself, and one can smoothly attach the wrench opening 40 over the rotating tube 22. The rotating tube 22 has a smooth cylindrical shape, and thus there is no need to orient the wrench 34 in accordance with the shape of the rotating tube 22. When the wrench 34 is rotated in a clockwise direction in Fig. 6, i.e., in the direction shown by the arrow in Fig. 3, the wedge member 44 rotates and shifts relatively in a counter-clockwise direction, through contact with the inner surface of the slack area 41 of the recess 42 and the outer surface 23 of the rotating tube 22, and by the biasing force of the spring 46. When the wedge member 44 shifts relatively in a counter-clockwise direction, the wedge member 44 is moved to the wedge area 43, and the wedge member 44 wedges between the wall of the wedge area 43 and the outer surface 23 of the rotating tube 22, whereby the wrench 34 and the rotating tube 22 are locked together regarding the same direction. Therefore, when the wrench 34 is further rotated in the same direction, the rotating tube 22 rotates clockwise with the wedge member 44. Through this rotation, the rotating tube 22 shifts toward the base end portion of the chuck body 10, and thereby the inner surface 18 of the chuck tube 16 contracts so that a machine tool, such as a drill or end mill, can be tightly secured within the chuck tube 16. When the wrench 34 is to be removed from the rotating tube 22, the wedge member 44 is shifted relatively in a clockwise direction by the counter-clockwise rotation of the wrench 34, and is moved to the slack area 41 of the recess 42. Since the slack area 41 is a deep recess, as stated above, the outer surface of the wedge member 44 does not wedge between the wall of the wedge area 43 and the outer surface 23 of the rotating tube 22, and thus the wrench 34 can be easily removed from the rotating tube 22. Thus, when the wrench 34 is rotated in a clockwise direction, the wedge member 44 wedges between the recess 42 and the rotating tube 22, and when the wrench 34 is rotated in a counter-clockwise direction, the wrench 34 slips as the wedge member 44 does not wedge between the recess 42 and the rotating tube 22. Therefore, the rotating tube 22 can be tightened by repeating rather small forward and backward rotations. When the machine tool is to be removed from the chuck tube 16, the wrench 34 is attached in an inverted manner to the rotating tube 22, i.e., from the side opposite to that used for securing the machine tool to the chuck tube 16, as shown in Fig. 8, and the wrench 34 is rotated counter-clockwise, i.e., in the direction shown by the arrow in Fig. 8. Thereby, the rotating tube 22 is rotated counter-clockwise by the wedge members 44 in the same manner as explained above, and the rotating tube 22 is shifted in the left hand direction in Fig. 1. The inner surface 18 of the chuck tube 16 expands, and the machine tool can be removed from the chuck tube 16. In this way, the wrench 34 can be easily attached to the rotating tube 22 without the need for adapting the wrench 34 to the shape of the rotating tube 22. Moreover, the outer surface 23 of the rotating tube 22 need not be knurled or provided with a recess to snap on the wrench 34, and thus the rotating tube 22 can be formed in a cylindrical shape with a smooth surface. Therefore, it is easy to manufacture the rotating tube 22, the airing noise during rotation of the rotating tube 22 can be prevented, and in particular, rotational balance can be maintained during high-speed rotation of the chuck body 10. Although the pair of handles 36 to rotate the wrench 34 are shown as extending symmetrically from the main body 39, the pair of handles 36 need not be formed in exactly the same way, and the number of handles may be alternatively one or three, so long as the rotating tube 22 can be rotated. While the wedge member 44 is shown as being formed with a cylindrical shape, the wedge member 44 can be of any shape, for example, spherical in shape, so long as it rotates. Moreover, while the rotating tube 22 (tightening member) is shown as being formed with a circular shape and is not knurled, the shape of this rotating tube is not intended to limit the claimed invention, and the rotating tube 22 may be uneven if necessary. While a coil spring is used as the spring 46 in this wrench, a plate spring may also be used. Fig. 9 illustrates part of another wrench that is also not an embodiment of the present invention but is merely usefull for understanding it. This wrench differs from the above-described wrench in that a retainer 58, the inside of which is circularly-shaped, is secured on the inner surface 38 of the wrench 34 and the wedge members 44 are housed in a plurality of recesses 64 formed in the retainer 58, and in that the spring 46' is a plate spring instead of a coil spring. The retainer 58 is formed in a circular shape, and is secured to the inner surface 38 of the wrench 34 by an outward projection 59 which engages with a recess 61 formed on part of the inner surface 38 of the wrench 34. The plate spring 46' is formed into an arch shape, the center portion of which projects toward the wedge member 44 to bias the wedge member 44 toward the wedge area 43. As stated above, the retainer 58 holds the wedge member 44 so that the wedge member 44 can move, and the slack area 41 and the wedge area 43 are configured with a relatively shallow recess 42 formed on the inner surface 38 of the wrench 34, and thus it is easier to manufacture the inner surface 38 of the wrench 34 than in the above-described wrench, where the both areas are formed with only the inner surface 38 of the wrench 34 holding the wedge members 44. Figs. 10 through 12 illustrate a wrench according to an embodiment of the present invention. This embodiment differs from the second-described wrench in that the retainer 58 is not secured to the wrench 34 such that the entire retainer 58 rolls along the circumference of the wrench 34 to move the wedge member 44 from the slack area 41 to the wedge area 43, and in that biasing means are provided on the retainer 58, rather than on each wedge member 44, so that each of the wedge members 44 is biased from the slack area 41 toward the wedge area 43. In this embodiment, the components that are the same as those in the first-described wrench are given the same numerals, and a description thereof has been omitted. The wrench 34 in this embodiment principally comprises a wrench body 35, a cylindrical retainer 58 provided at the inner surface 38 of the wrench body 35, a spring 60 to bias the retainer 58 in the direction of the circumference, and a lid member 62 to hold the spring 60 and the retainer 58. More specifically, the rotatable retainer 58 is provided on the inner surface 38 of the wrench body 35 in the direction of the circumference, in which the plurality of recesses 64 to house the wedge members 44 are provided with predetermined distances therebetween on the circumference of the retainer 58 so that the wedge members 44 are rotatable but not movable within the respective recesses 64 as they are housed in the recesses 64. By this configuration for keeping the wedge members 44 in the retainer 58, in this embodiment, the plurality of wedge members 44 move in the direction of the circumference together with the retainer 58. In this embodiment, the slack area 41 and the wedge area 43 are also formed by a recess 42 on the inner surface 38 of the wrench body 35. Each recess 42 in this embodiment is formed to define the slack area 41 in the middle and the wedge areas 43 on both opposite sides for the purposes of easy manufacture. Reference numeral 63 denotes a stopper to keep the wedge member 44 and the retainer 58 from moving toward one of the wedge areas 43 in the clockwise direction, so that rotation of the wrench 34 in a counter-clockwise direction does not cause the wedge member 44 to be in the wedge area 43 and lock the wrench 34 with the rotating tube 22. As shown in Fig. 13, the spring 60 is formed into an almost circular shape, and small projections 66, 68 are provided on both ends. One of the small projections 66 is connected to an engagement recess (not shown) formed on the top surface of the retainer 58, and the other small projection 68 is connected to an engagement recess (not shown) formed on the lid member 62. As such, the retained 58 is always biased so that the wedge member 44 moves from the slack area 41 to the wedge area 43. According to this wrench, the wedge member 44 may be biased from the slack area 41 to the wedge area 43 by using one spring, thereby reducing the number of components and simplifying assembly. The present invention provides a wrench which can be easily attached to a tightening member and which enables easier manufacture of a tightening member, and also provides a wrench which can be easily tightened even when there is an obstacle around a tightening member.

Claims: A wrench for tightening a tightening member (22) to another member by rotating said tightening member (22) around its own axis, comprising: a body (35) having an inner surface (38) to be attached to an outer surface (23) of said tightening member (22); at least one rotatable wedge member (44) provided on said inner surface (38) of said body (35) having a wedged state in which it wedges between said outer surface (23) of said tightening member (22) and said inner surface (38) of said body (35) at least one recess (42) with a circularly-curved cross section formed on said inner surface (38) of said body (35) for receiving said at least one wedge member (44), each recess (42) including a slack area (41) for housing said wedge member (44) in a non-wedged state and a first wedge area (43) flanking one side of said slack area (41), the first wedge area being for housing said wedge member (44) in said wedged state, the depth of said slack area (41) being greater than that of said first wedge area (43); and a retainer (58) disposed on said inner surface (38) of said body (35) and having a respective aperture (64) to maintain said at least one wedge member (44) in a predetermined position along said inner surface, said retainer (58) being configured so as to be movable in the direction of the circumference of said inner surface (38) of said body (35) to a predetermined extent, for moving said wedge member from said slack area to said first wedge area upon rotation of said body in at least one direction whereby said wedge member (44) protrudes from said retainer into the wrench opening (40) in which the tightening member (22) is received characterised by:- said at least one recess (44) having a second wedge area (43) flanking said slack area on a side opposite said one side; and at least one pin-like stopper (63) for preventing said at least one wedge member (44) and the retainer (58) from moving from said slack area to said second wedge area (43). A wrench according to claim 1, wherein said at least one wedge member (44) is cylindrical in shape. A wrench according to claim 1, wherein said at least one wedge member (44) is spherical in shape. A wrench according to claim 1, wherein said inner surface (38) of said body (35) is formed so as to surround completely said outer surface (23) of said tightening member (22). A wrench according to any foregoing claim, wherein said retainer (58) is annular, and further comprising a biasing means for biasing said retainer (58) such that said at least one wedge member (44) is biased from said slack area (41) towards said wedge area (43), said biasing means comprising a ring-shaped spring (60) corresponding in shape to that of said retainer (58).

Inventors: KITAMURA YASUHIKO, MATSUBARA MASAYUKI, KITAMURA, YASUHIKO, MATSUBARA, MASAYUKI, KITAMURA, YASUHIKO, C/O DAISHOWA SEIKI K.K., MATSUBARA, MASAYUKI, C/O DAISHOWA SEIKI K.K.
Applicants: DAISHOWA SEIKI, DAISHOWA SEIKI KABUSHIKI KAISHA
Application year: 1994
Main classification: B25B13
IPC codes: B25B13